Malaria is one of the most serious human infectious diseases caused by parasitic protozoa. It is estimated that several hundred million people are infected with malaria every year, of which several million people die. This threat has been continued since prehistoric times in the tropical zone. To date, main infection area has limited to the tropical zone and the subtropical zone. However, due to global warming, it is feared that malaria may extend to the temperate zone. In addition, together with spread of species that are resistant to conventional drugs, development of new effective medicines has been a pressing need.
Malaria parasites engulf and digest erythrocytes and take the protein thereof as a nutrient source. At this time, hemoglobin, heme, remained in the parasites is harmful to the parasites. Therefore, the parasites have a system for polymerizing heme and converting it into a sand-like form so as to carry out detoxification and excretion of the heme. It is thought that a quinoline antimalarial drug developed from quinine gains drug efficacy because it has an affinity to heme mainly on the basis of a π-π stacking ability and inhibits the polymerization of heme, thus making it impossible to carry out detoxification of harmful heme (see FIG. 1).